#demo5 {
  .demo-wrapper > div {
    display: flex;
    font-size: 18px;
    flex-shrink: 0;
    flex-wrap: wrap;
    margin: 0 auto;
  }

  .box {
    align-items: center;
    box-sizing: border-box;
    color: #333;
    display: flex;
    flex-grow: 0;
    flex-shrink: 0;
    justify-content: center;
    outline: 1px solid #333;
    text-align: center;
    @for $i from 0 through 11 {
      $pcent: 100% / (3 + $i * 3);
      &.file#{$i} {
        font-size: 1em - $i / 11;
        height: $pcent;
        width: $pcent;
      }
    }
  }
}
